Alcohols Flashcards
What is an addition reaction?
A reaction where 2 or more molecules join together to give a single product.
What is an elimination reaction?
A reaction where a multiple covalent bond is formed in a molecule by the removal of another, usually smaller, molecule.
What is a substitution reaction?
A reaction where an atom or group of atoms in a molecule is replaced by another atom or group of atoms.
In dehydration reactions, why is phosphoric acid used instead of sulfuric acid?
- It’s safer and produces a less messy reaction because it’s a less strong oxidizing agent. Using sulfuric acid increases the carboxylic acid product of this reaction (formed by oxidation)
- We get less acid contaminants.
Why are alcohols miscible with water?
Because hydrogen bonding can occur between the water and alcohol molecules.
Why do alcohols have a high boiling point?
The hydroxyl group has a polar covalent bond, so can form hydrogen bonds with other alcohol molecules.
What happens when you partially oxidise a primary alcohol?
Primary alcohol + (O) = aldehyde + water
What happens when you oxidise an aldehyde?
Aldehyde + (O) = carboxylic acid
What happens when you oxidise a secondary alcohol?
Secondary alcohol + (O) = ketone + water
Why are tertiary alcohols not easily oxidized?
Oxidisation requires a C-C to break, rather than a C-H.
General formula for ketone
R2CO
General formula for aldehyde
RCHO
General formula for carboxylic acids
RCOOH
What is tollens reagent
gentle oxidizing agent
silver nitrate and aqueous ammonia
What happens in the tollens test
On warming an aldehyde with Tollen’s reagent, a deposit of metallic silver is formed on the inside of the test tube.
